Model train control



0a. 26, 1965 w. J. JORDAN, JR 3,214,597

MODEL TRAIN CONTROL Filed Sept. 11, 1961 N "4 N g5 -i I \O INVENTOR.WILLIAM J. JORDAN JR.

MZJMSM 4211M Afforn us United States Patent 3,214,597 MODEL TRAINCONTROL William J. Jordan, Jr., Indianapolis, Ind,, assignor to TheBuehler Corporation, Indianapolis, Ind., a corporation of Indiana FiledSept. 11, 1961, Ser. No. 137,303 5 Claims. (Cl. 30743) This inventionrelates generally to model electric trains and more particularly to anelectronic controller for the control of operation, and speed of modelelectric trains.

In model railroading, great emphasis is placed on the precision of scaleof the miniature trains. Many of the trains are of the size designatedH.O. gauge. They employ direct current electric motors. Considerabletime, effort, and expense are involved in making the model trains, thetrack layout, surrounding scenery, and all other items associated withthe model railroad, precisely to scale. It follows that there isconsiderable interest in operating the trains at scale speeds, andsimulating actual operating conditions, both as to acceleration anddeceleration of the model trains.

It has been conventional practice to use controllers for model trainshaving full wave direct current control voltage sources. In order toobtain very slow motion of the model train during starting thereof, thepractice has been to use half-Wave surges in the controller outputwhereby surging in the model locomotive motor is sulficient to overcomestatic friction and place a train in motion though at a low speed. Thehalf-Wave energy is obtained normally by using a bridge rectifier, andclosing the shorting bar for full-wave operation upon achievement of adesired speed of the train.

The conventional practice has had several serious disadvantages. Duringthe starting of the train, the half- Wave energy has caused rapid heatbuild-up in the model motors, thus limiting the time during which atrain may be gradually accelerated. If, by oversight, the controller isallowed to remain in some position of half-wave application to the motorfor an extended period of time, the motor or motors would be ruined byoverheating.

A further disadvantage of conventional practice is that afteracceleration of the locomotive by the half-wave application, uponclosing of the bar in the rectifier bridge, the voltage output to theelectric motors practically doubles, causing the train to jump. Thus inaddition to excessive heat generation in the model train motors,conventional practice makes precise and realistic control of the trainsvery difiicult.

It is also conventional practice to use a rheostat in series with thesupply to the tracks. Thus as the load on the motors increases duringuphill operations, the available voltage to the motors is substantiallydecreased by the additional drop through the rheostat. Similarly, duringdownhill operation, the voltage to the motors substantially increases,thus causing extreme speedups of the train during downhill operation.The elfect is to require continuous attention by the model railroadoperator during uphill and downhill operation of the trains in order tomaintain realistic speeds.

There is a further disadvantage to the conventional practice of using arheostat in series with the supply to the tracks. It places a severelimitation on the number of motors which can be used simultaneously andoperated at maximum speeds. Obviously, the more motors that are inoperation, the greater will be the voltage drop in the rheostat, makingavailable less voltage for motor operation.

It is, therefore, a general object of this invention to provide animproved control device for model railroads.

It is a further object of this invention to provide a 3,214,597 PatentedGet. 26, 1965 control device for model trains which greatly facilitatesthe achievement of realism in the operation of the trains.

It is a further object of this invention to provide a control device formodel trains whereby a steady and continuous increase of speed of modeltrains can be obtained from the condition of the train at rest to thecondition of the train operating at maximum scale speed.

It is a further object of this invention to provide a control device formodel trains whereby the voltage avail able to the train motor is notappreciably influenced by the load thereon.

It is a still further object of this invention to provide a controldevice having the aforementioned capability and the ability to produce anegligible temperature rise above normally expected temperatures.

It is a still further object of this invention to provide a model traincontrol which does not require either a battery supply for controlvoltage source or a filtered direct-current supply for the controlvoltage source.

It is a still further object of this invention to provide a model traincontrol device adapted to employ an unfiltered full-wave direct-currentinput.

It is a still further object of this invention to provide a model traincontrol device utilizing a half-wave control voltage source. It is astill further object of this invention to provide a model train controldevice capable of overcoming efiects of dirt on tracks, switch contacts,and the like.

Described brietly, a typical embodiment of this invention includes acontrol transistor having its emittercollector path in a coupling to arectified, unfiltered direct-current power supply. The output of thedevice is obtained from the direct current power supply and includes apass transistor having its emitter-collector path in series with theoutput circuit and returned to the ground side of the DC. power supply.Current conduction of the pass transistor is controlled by a couplingfrom the emitter of the control transistor to the base of the passtransistor.

The control potential for the control transistor is obtained from apotentiometer having its resistance element connected across a source ofhalf-wave energy obtained from a half-wave rectifier, voltage dividercombination connected across an A.C. input. An R-C Waveshapingcombination is coupled between the potentiometer and the base of thecontrol transistor whereby the ripple from the DC. power supply ismodified to produce a pulse output from the emitter of the controltransistor. This pulse output is just twice the frequency of the A.C.input to the control voltage source and by application to the base ofthe pass transistor, provides a pulsed output to the electric trainmotors at twice the frequency of the A.C. input to the control voltagesource. By varying the setting of the potentiometer in the con trolvoltage source, the speed of the trains can be controlled. The pulseduration is equal to two-thirds of one-half cycle.

The invention may be better understood from a consideration of thefollowing detailed description when read in accordance with the attacheddrawing which the single figure shows schematically a typical embodimentof the circuit of this invention.

Referring to the drawing, output terminals 11 and 12 are provided forconnection to the tracks of the model railroad layout. The power supply13, is a non-filtered direct-current source of electrical energy. Forthe typical model railroad application, an 18 volt source is desirable.Terminal 14 of the source is grounded and terminal 16 thereof providesan input to the circuit of this invention, which may be typically of theform designated by reference numeral 17 and indicative of a full-waveripple.

A control transistor 18, of the PNP type, is provided in a couplingacross the source 13. The emitter of transistor 18 is connected throughresistance 19 to the output 16 of the source 13, and the collector oftransistor 18 is grounded. Control of this transistor is provided inparticularly novel fashion, as will become apparent as th descriptionproceeds.

Input lines 21 and 22 are provided, for coupling a 'source 23 ofalternating current electrical energy to the circuit. Typically thissource may provide 115 volt, 60 cycle alternating current energy. Ahalf-wave rectifier and voltage divider combination is providedincluding the diode 24, coupled in series across the lines 21 and 22,with the resistances 26 and 27. Accordingly, a half-wave voltage isprovided between the line 22 and the junction 28 between resistors 26and 27. By way of example, the values are established to provide avoltage of 13 volts. A potentiometer 31 is provided with a winding 32connected across the resistor 27. Wiper 33 of potentiometer 31 iscoupled through resistor 34 to the base electrode of transistor 18. Bythe provision of conductor 36 between the input line 16 and the junction28, a control circuit through transistor 18 is provided, and the settingof potentiometer 31 provides an adjustable control thereof.

A capacitor 37 is coupled between the wiper 33 of potentiometer31, andground. The combination of capacitor 37 and resistor 34 provides a pulseforming network whereby the voltage waveform of the emitter oftransistor 18 taken with respect to input line 16 may be made of theform designated by reference numeral 38.

A pass transistor 41 is provided, having a collector connected to groundand an emitter coupled through the circuit breaker 42 to terminal 43 ofthe double-pole, double-throw direction reversing switch 44. The otherterminal 46 of switch 44 is connected by way of conductors 47 and 36directly to the input line 16. With the movable contacts of switch 44 inthe position shown, terminal 46 thereof is connected to the outputterminal 11, and terminal 43 thereof is connected to the output terminal12. The base electrode of transistor 41 is coupled through conductor 48to the emitter electrode of transistor 18. It should be apparent at thispoint, that transistor 41 is in the load circuit of this invention, andcontrol thereof by control transistor 18, provides the control for theoutput voltage at terminals 11 and 12. The wave form typically obtainedat the output terminals 11 and 12 according to this invention, isdesignated by reference numeral 49. This voltage is a pulsating DCvoltage, having twice the frequency of the full-wave non-filtered directcurrent input available from source 13. As a typical example, where theinput to lines 14 and 16 represents a non-filtered fullwave directcurrent derived from the 115 volt alternating current source, the outputacross terminals 11 and 12 would consist of voltage pulses where thepulse rate is 120 per second. Control of the output voltage level isprovided by way of potentiometer 31, which therefore has the operatingrole of the train speed control. Reversal of direction of operation ofthe trains, may be obtained by merely moving the movable contacts ofswitch 44 to engagement with the terminals 51 and 52 thereof.

By virtue of the novel construction of the present invention, all of theforegoing objects are achieved. The pulsating voltage wave form acrossthe output terminals 11 and 12 is available at all speeds, though ofcourse the magnitude of the pulses is less as the controlling voltage islowered by adjustment of potentiometer 31. It should be recognized thatthe capacity of the circuit can be increased -by addition of transistorsin parallel with transistor 41, if desired. For best results, the valueof the voltage provided across resistor 27 of the voltage divider,should be slightly less than the voltage input from the power supply 13.For example, where the power supply voltage is 18 volts DC, the voltageacross resistor 27 should be no greater than 16 /2 volts.

Forpurposes of example only, the following is a list of components andvalues which have been successfully used in the practice of thisinvention.

Perhaps it should be mentioned that NPN transistors can be employedaccording to this invention as readily as PNP transistors. Moreover,though the invention has been disclosed as particularly beneficial inthe operation of model electric train motors, which are usually of thepermanent magnet type DC. motor, it is conceivable that this inventionmay be beneficial in the operation of other DC. motors also.

While the invention has been disclosed and described in some detail inthe drawings and foregoing description, they are to be considered asillustrative and not restrictive in character, as other modificationsmay readily suggest themselves to persons skilled in this art and Withinthe broad scope of the invention, reference being had to the appendedclaims.

The invention claimed is:

1. A model train control device comprising: I

first input means for direct current electrical energy;

a first electron discharge device having a current flow path thereincoupled in series with said input means and having a first resistancemeans in series therewith, and said discharge device having a controlelectrode;

second input means for alternating current electrical energy;

a rectifier coupled to said alternating current input means to provide adirect current voltage source;

control circuit means coupling said direct current source to the controlelectrode of said electron discharge device to provide a source ofcontrol voltage for said device; said control circuit means including apulse forming network coupled to the control electrode of said firstdevice to provide voltage pulses across said first resistance means; Ioutput terminals for a load, one of said terminals being coupled to saidfirst input means;

a second electron discharge device coupled between said first inputmeans and another of said output ter minals, said second device having acontrol electrode coupled to said first resistance means whereby a pulsevoltage is provided at said output terminals and is controllable by saidcontrol voltage source.

2. A model train control device comprising:

first input means for direct current electrical energy;

a first transistor having an emitter-collector path coupled in serieswith a first resistance means and said input means, and said firsttransistor having a base electrode;

second input means for alternating current electrical energy;

a rectifier coupled to said alternating current input means to provide adirect current voltage source; control circuit means for said firsttransistor and coupling said direct current voltage source to said firsttransistor, said control circuit means including said first resistanceconnected between said source and the emitter of said first transistor,and said control circuit means including adjustable means coupling saiddirect current voltage source to the base of said first transistor toprovide a variable source of control voltage for said transistor;

and said control circuit means including a pulse forming networkconnected between said adjustable meant: and the base of said firsttransistor to provide voltage pulses at the emitter of said firsttransistor;

output terminals for a load, one of said terminals being coupled to saidfirst input means;

a second transistor having an emitter-collector path coupled betweensaid first input means and another of said output terminals, said secondtransistor having a base electrode coupled to the emitter of said firsttransistor, whereby a pulse voltage is provided at said output terminalsand is controllable by said adjustable means.

3. A model train control device comprising:

first input means for direct current electrical energy having afull-wave ripple;

a first transistor having an emitter-collector path coupled in serieswith a first resistance means and said input means, and said firsttransistor having a base electrode;

second input means for alternating current electrical energy of the samefrequency as the full-wave ripple at said first input means;

a half-wave rectifier coupled to said alternating current input means toprovide a half-wave direct current voltage source;

control circuit means for said transistor and coupling said directcurrent voltage source to said first transistor, said control circuitmeans including said first resistance connected between said source andthe emitter of said first transistor, and said control circuit meansincluding adjustable means coupling said half-wave source to the base ofsaid first transistor to provide a variable source of control voltagefor said transistor;

and said control circuit means including a pulse forming networkconnected between said adjustable means and the base of said firsttransistor to provide voltage pulses at the emitter of said firsttransistor at twice the frequency of the full wave ripple at said firstinput means;

output terminals to supply model trains, one of said terminals beingcoupled to said first input means;

a second transistor having an emitter-collector path coupled betweensaid first input means and another of said output terminals, saidsecondtransistor having a base electrode coupled to the emitter of saidfirst transistor, whereby a pulse voltage having twice the frequency ofthe full-wave ripple at said first input means is provided at saidoutput terminals and is controllable by said adjustable means to controlthe speed of model trains.

4. A model train control device comprising:

first input means for ripple-bearing direct current electrical energy;

a first electron discharge device having a load circuit including saidinput means and having a control electrode;

direct current voltage source coupled in a control circuit with saidcontrol electrode to provide a source of control voltage for saidelectron discharge device;

a pulse forming network in said control circuit and coupled to thecontrol electrode of said electron discharge device to provide voltagepulses in said load circuit;

output terminals for a load, one of said terminals being coupled to saidfirst input means;

and a second electron discharge device having a load current conductingpath coupled between said first input means and another of said outputterminals, said second device having a control electrode coupled in theload circuit of said first electron discharge device, whereby a directcurrent pulse voltage is provided at said output terminals and iscontrollable by said control voltage source.

5. A model train control device comprising:

a first energy source providing direct current electrical energy bearinga fullwave ripple;

a first electron discharge device having an energy flow path thereincoupled in series with said first source, said first electron dischargedevice having a control electrode for controlling energy flowing in saidpath;

a second energy source providing alternating current electrical energy;

a half-wave rectifier coupled to said second energy source to provide athird energy source producing half-wave direct current energy;

coupling means providing a direct current coupling between said thirdenergy source and said control electrode, said coupling means includingan adjustable element to change the energy flowing in said path;

aload;

a second electron discharge device having an energy flow path thereincoupled in series with said load an d said first energy source to supplydirect current energy from said first source to said load through thesaid flow path of said second electron discharge devico, said secondelectron discharge device having a cunttrol electrode;

and means coupling the said energy flow path of said, first electrondischarge device in a series circuit with the control electrode of saidsecond electron dis charge device to provide a control circuit for saidlsecond electron discharge device, whereby energy supplied to said loadis controllable by said adjust able element.

References Cited by the Examiner UNITED STATES PATENTS Re. 24,678 8/59Pinckaers 307-88.5 2,837,740 6/58 Riddle 307-88.5 2,864,978 12/58 Frank307--88.5 2,911,566 11/59 Taylor 3O788.5 3,044,004 7/62 Sicard 307-88.5

LLOYD MCCOLLUM, Primary Examiner.

ILTO 0- H R H I L Q xam ner,

1. A MODEL TRAIN CONTROL DEVICE COMPRISING: FIRST INPUT MEANS FOR DIRECTCURRENT ELECTRICAL ENERGY; A FIRST ELECTRON DISCHARGE DEVICE HAVING ACURRENT FLOW PATH THEREIN COUPLED IN SERIES WITH SAID INPUT MEANS ANDHAVING A FIRST RESISTANCE MEANS IN SERIES THEREWITH, SAID DISCHARGEDEVICE HAVING A CONTROL ELECTRODE; SECOND INPUT MEANS FOR ALTERNATINGCURRENT ELECTRICAL ENERGY; A RECTIFIER COUPLED TO SAID ALTERNATINGCURRENT INPUT MEANS TO PROVIDE A DIRECT CURRENT VOLTAGE SOURCE; CONTROLCIRCUIT MEANS COUPLING SAID DIRECT CURRENT SOURCE TO THE CONTROLELECTRODE OF SAID ELECTRON DISCHARGE DEVICE TO PROVIDE A SOURCE OFCONTROL VOLTAGE FOR SAID DEVICE; SAID CONTROL CIRCUIT MEANS INCLUDING APULSE FORMING NETWORK COUPLED TO THE CONTROL ELECTRODE OF SAID FIRSTDEVICE TO PROVIDE VOLTAGE PULSES ACROSS SAID FIRST RESISTANCE MEANS;OUTPUT TERMINALS FOR A LOAD, ONE OF SAID TERMINALS BEING COUPLED TO SAIDFIRST INPUT MEANS; A SECOND ELECTRON DISCHARGE DEVICE COUPLED BETWEENSAID FIRST INPUT MEANS AND ANOTHER OF SAID OUTPUT TERMINALS, SAID SECONDDEVICE HAVING A CONTROL ELECTRODE COUPLED TO SAID FIRST RESISTANCE MEANSWHEREBY A PULSE VOLTAGE IS PROVIDED AT SAID OUTPUT TERMINALS AND ISCONTROLLABLE BY SAID CONTROL VOLTAGE SOURCE.